MERRA-2 Global Aerosol Optical Depth Analysis at 3-Hour Intervals

MERRA-2 instU_2d_gas_Nx provides instantaneous, 2-dimensional monthly diurnal means for aerosol optical depth analysis and its assimilation increment. The dataset covers the period from 1980 to the present, with data produced approximately three weeks after each month ends. NASA's Global Modeling and Assimilation Office generated this reanalysis using the Goddard Earth Observing System Model version 5.12.4.

Use Cases

• Analyze diurnal cycles of aerosol optical depth using the 3-hourly data fields (00:00, 03:00, ..., 21:00 UTC).
• Validate climate model aerosol outputs by comparing against the assimilation aerosol optical depth analysis field.
• Study long-term trends in atmospheric particulates from 1980 to present using the monthly mean time series.
• Assess spatial patterns of aerosol loading at the global 0.625 x 0.5 degree resolution.

Strengths

• Provides continuous global coverage from 1980 to the present, enabling long-term trend analysis.
• Offers high temporal resolution with data fields at 3-hour intervals (00:00, 03:00, ..., 21:00 UTC).
• Data is produced by NASA GMAO using a consistent reanalysis system (GEOS 5.12.4).

Limitations

• Data has a latency of approximately three weeks after the end of each month, limiting real-time applications.
• Specific row counts, file sizes, and detailed column schema are not provided in the input.
• Users must check for reprocessing events, as filenames differ between original and reprocessed data.

Provenance

Source

NASA Global Modeling and Assimilation Office (GMAO) via the GES DISC.

Collection Method

Produced using the Goddard Earth Observing System Model (GEOS) version 5.12.4 for atmospheric reanalysis.

Time Range

1980 to present.

Freshness

Updated monthly with ~3-week latency.

Geography

Global coverage at 0.625 x 0.5 degree resolution.